1. Field of the Invention
The present invention relates to a schottky barrier diode and a method of making the same.
2. Description of Related Art
FIG. 6 is a conventional schottky barrier diode (hereinafter called “schottky diode.”) (See JPA-2004-221513 for example.) The schottky diode X shown in this figure uses a SiC substrate 91 as a basis. The SiC substrate 91 has a (0001) Si surface 91b and a (000-1) C surface 91a. The (0001) Si surface 91b is formed with an epitaxial layer 92. The epitaxial layer 92 is formed with a guard ring 92a. On the epitaxial layer 92, an insulation layer 93, a schottky electrode 94 and a metal layer 95 are formed in lamination. A contact hole 93a is made in the insulation layer 93 to provide contact between the schottky electrode 94 and the epitaxial layer 92. The contact made by the schottky electrode 94 and the epitaxial layer 92 is schottky contact. The (000-1) C surface 91a is formed with an ohmic electrode 96. The contact made by the ohmic electrode 96 and the SiC substrate 91 is ohmic contact. The schottky diode X is used to provide a relatively high-speed switching in electric circuits.
In the schottky diode X, the schottky barrier height between the schottky electrode 94 and the epitaxial layer 92 must have an appropriate value in order to reduce leak current caused by reverse voltage. However, in the above-described design where the epitaxial layer 92 is formed on the (0001) Si surface 91b, the best achievable schottky barrier height was about 1.0 eV, and for this reason, it has not been possible in the schottky diode X to sufficiently reduce the leak current caused by reverse voltage.